Table Of ContentDevelopment of a Multi-Component Model Structure for
Autogenous and Semi-Autogenous Mills
Marcos de Paiva Bueno
B. Eng. (Mining)
A thesis submitted for the degree of Doctor of Philosophy at
The University of Queensland in 2013
Sustainable Minerals Institute, Julius Kruttschnitt Mineral Research Centre
Abstract
Autogenous (AG) and semi-autogenous (SAG) grinding mills have become popular in the mining
industry for their ability to provide a high reduction ratio and deal with high tonnage projects in a
compact plant layout. AG mills exclusively use ore as grinding media, while in SAG mills steel
balls are added as a supplement. For more than 40 years researchers have been developing
mathematical models to assist in the design and optimization of AG/SAG mill operations.
The existing mathematical models to date are incapable of dealing with multi-component feeds. In
other words, they consider a homogenous feed, which is an unrealistic scenario for some mining
operations. Occasionally, the run of mine feed is constituted of different ore types which have
different physical characteristics. The performance of AG/SAG mills is intrinsically related to the
feed material as it determines the mill load (grinding media) constitution. Hard ores usually build up
in the mill contents and limit throughput. However, these well-known effects have not been
investigated in detail or considered in any of the current models.
Therefore, a research programme was conducted to understand, describe and model the interactions
between the various components inside an AG/SAG mill in terms of particle breakage,
transportation and classification, and to provide a true multi-component model structure that
considers size and component distributions (A two-dimensional structure - 2D).
During this research a comprehensive testwork program was conducted to investigate the effects of
multi-component feeds on autogenous and semi autogenous grinding performance. Tests were
conducted at laboratory, pilot and industrial scale, using artificial mixtures and real ore blends.
During the laboratory investigations, a new SAG Locked Cycle Test procedure was developed. Two
pilot plant campaigns were carried out using real multi-component ores. Additionally, the entire
mill contents of an autogenous industrial mill was measured in terms of size and mineral
distribution, during a survey conducted at LKAB operations in Sweden.
The breakage and transport in AG/SAG mills was found to depend on the physical properties and
proportion of the different components in the mill feed. Consequently, the overall performance of
an AG/SAG mill (throughput, product size and power draw) is dependent on the feed composition
and it could be predicted using a multi-component model.
i
The new multi-component model structure (2D) was developed by modifying Leung’s AG/SAG
model (1987) to accommodate simultaneous iterations with different ore types, allowing for the
specification of the data on a component by size basis. The new model is based on the independent
breakage and transport of components with substantially different physical properties and on the
assumption of fully liberated (i.e. independent) components. The model was refined and validated
using multi-component data obtained through the extensive experimental campaign. The model is
capable of accurately describing the assay-by-size data, as well as the changes in throughput
capacity, mill load and product caused by variations in the mill feed composition.
ii
Declaration by author
This thesis is composed of my original work, and contains no material previously published or
written by another person except where due reference has been made in the text. I have clearly
stated the contribution by others to jointly-authored works that I have included in my thesis.
I have clearly stated the contribution of others to my thesis as a whole, including statistical
assistance, survey design, data analysis, significant technical procedures, professional editorial
advice, and any other original research work used or reported in my thesis. The content of my thesis
is the result of work I have carried out since the commencement of my research higher degree
candidature and does not include a substantial part of work that has been submitted to qualify for
the award of any other degree or diploma in any university or other tertiary institution. I have
clearly stated which parts of my thesis, if any, have been submitted to qualify for another award.
I acknowledge that an electronic copy of my thesis must be lodged with the University Library and,
subject to the General Award Rules of The University of Queensland, immediately made available
for research and study in accordance with the Copyright Act 1968.
I acknowledge that copyright of all material contained in my thesis resides with the copyright
holder(s) of that material. Where appropriate I have obtained copyright permission from the
copyright holder to reproduce material in this thesis.
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Publications during candidature
Peer-reviwed papers:
Bueno, M, Shi, F, Kojovic, T & Powell, MS 2010, 'Investigation on multicomponent semi-
autogenous grinding', paper presented to XXV International Mineral Processing Congress,
Brisbane, September 6 - 10, 2010. – Partially incorporated in Chapter 3.
Bueno, MP, Kojovic, T, Powell, MS & Shi, F 2012, 'Multi-component AG/SAG mill model',
Minerals Engineering, vol. in press. – Partially incorporated in Chapters 7 and 8.
Bueno, MP & Powell, MS 2012, 'How to Use Hard Ore Components as Grinding Media', paper
presented to 11th AusIMM Mill Operators' Conference, Hobart, Tasmania. – Partially incorporated
in Chapter 8.
Bueno, MP & Lane, G 2012, 'Key Drivers of Energy and Cost Efficiency in AG/SAG circuits',
paper presented to 11th AusIMM Mill Operators' Conference, Hobart, Tasmania. – Not relevant to
the thesis.
Conference papers:
Bueno, M, Neva, E, Powell, MS, Fredriksson, A, Kojovic, T, Worth, J, Shi, F, Adolfsson, G,
Partapuoli, Å, Wikström, P, Olofsson, M & Tano, K 2011, 'The Dominance of The Competent',
paper presented to International autogenous and semiautogenous grinding and high pressure
grinding roll technology, Vancouver, September 25 - 28, 2011. – Partially incorporated into
Chapters 5 and 6.
Bueno, M, Shi, F, Kojovic, T, Powell, MS, Sweet, J, Philips, D, Durant, B & Plint, N 2011, 'Multi-
Component Autogenous Pilot Trials', paper presented to International autogenous and
semiautogenous grinding and high pressure grinding roll technology, Vancouver, September 25 -
28, 2011. – Partially incorporated into Chapters 4 and 6.
Bueno, M & Lane, G 2011, 'A Review of 10 Years of AG/SAG Pilot Trials', paper presented to
International autogenous and semiautogenous grinding and high pressure grinding roll technology,
Vancouver, September 25 - 28, 2011. – Not relevant to the thesis.
Report chapter:
Bueno, MP, Shi, F, Kojovic, T & Powell, MS 2011, 'Development of a Multi-Component AG/SAG
Model', in P9O Project Final Technical Report, AMIRA, pp. 205-41. – Partially incorporated in
Chapter 6.
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Publications included in this thesis
Bueno, M et al. (2010) – Partially incorporated in Chapter 3
Contributor Statement of Contribution
Bueno, M (Candidate) Designed and conducted the experiments;
Analysed the data;
Wrote the paper.
Shi, F, Kojovic, T and Powell, MS Reviewed the experimental design, results and
the paper.
Bueno, M, Neva, E, et al. (2011) – Partially incorporated into Chapter 5 and 6
Contributor Statement of Contribution
Bueno, M (Candidate) Conducted the industrial survey;
Designed and conducted the pilot tests;
Analysed the data;
Wrote the paper.
Shi, F, Kojovic, T and Powell, MS Reviewed the experimental design, results and
the paper
Kojovic, T. Assisted on site with establishing the pilot work
Worth, J Phisically assisted in the industrial survey at
LKAB Kiruna concentrator and processing the
samples at JKMRC laboratory.
Wikström, P Phisically assisted in the industrial survey at
LKAB Kiruna concentrator.
Neva, E and Olofsson, M Phisically assisted in the pilot plant campaign
and processing the samples the at LKAB
research facilities.
Fredriksson, A, Adolfsson, G, Partapuoli, Å and Managed the resourses and logistics at LKAB to
Tano, K make this work possible.
Bueno, M, Shi, F, et al. (2011) – Partially incorporated into Chapter 4 and 6
Contributor Statement of Contribution
Bueno, M (Candidate) Designed and conducted the pilot tests;
Analysed the data;
Wrote the paper.
Shi, F. and Kojovic, T Reviewed the experimental design, results and
the paper
Powell, MS Assisted with establishing experimental
technique, and experimental design. Reviewed
results and paper.
Sweet, J Phisically assisted in the pilot plant campaign
and processing the samples at Anglo Platinum
research facilities.
Philips, D Conducted all the assays for Chrome at the
Anglo Platinum Laboratories
Durant, B and Plint, N 2011 Managed the resourses and logistics at Anglo
Platinum to make this work possible.
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Bueno, MP et al. (2011) – Partially incorporated in Chapter 6
Contributor Statement of Contribution
Bueno, MP (Candidate) Analysed the data;
Wrote the report.
Shi, F, Kojovic, T and Powell, MS Reviewed the results and the report.
Bueno, MP et al. (2012) – Partially incorporated in Chapter 7 and 8
Contributor Statement of Contribution
Bueno, MP (Candidate) Analysed the data;
Developed the model;
Wrote the paper.
Shi, F, Kojovic, T and Powell, MS Reviewed the results and the paper.
Bueno, MP and Powell (2012) – Partially incorporated in Chapter 8
Contributor Statement of Contribution
Bueno, MP (Candidate) Wrote the paper.
Powell, MS Reviewed the paper.
Contributions by others to the thesis
Mr. Michal Andrusiewicz assisted in programming the code of the new multi-component model and
implementing it into the MDK simulation platform.
Statement of parts of the thesis submitted to qualify for the award of another degree
None.
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Acknowledgements
Firstly, I thank to God the Almighty, who is worthy of my eternal praise and love.
To the following institutions and people, I am sincerely grateful for their contributions.
The Julius Kruttschnitt Mineral Research Centre for offering a scholarship and providing
world class conditions for me to conduct this PhD program. It is an honour to become
alumni of such reputable research institution.
AMIRA and all sponsors of P9O project, especially LKAB and Anglo American, for their
support and creating the opportunities to conduct this research.
My academic supervisor, Dr. Frank Shi for his precise advice, encouragement, and patience
in dealing with my sometimes overly enthusiastic behaviour.
Dr Toni Kojovic, my co-advisor, for his friendship, enthusiasm and inspiring guidance
throughout this thesis. Particularly for his assistance during the pilot tests in Sweden and
helpful advice in modelling challenges.
Professor Malcolm Powell for all the great time, philosophic conversations, brainstorms,
academic guidance, technical discussions, and of course, beer drinking! It was a pleasure to
meet you my brother.
Professor Tim Napier Munn for his guidance and suggestions on the structure of this thesis.
Mr Michael Andrusiewicz for his valuable assistance when developing the MDK program.
Students and staff of JKMRC for the awesome times we spent together, as well as all
kindness and support provided. You made my research life more enjoyable.
Uncle Aldemir for his influence and support throughout my life.
My wife Mirella, who has left everything behind to marry me and come to Australia, for
loving me and being my best friend (making me smile even when things turn bad). To you I
also apologise, for making you feel the bitterness of my frustrations during this thesis.
Lastly and most of all, I would like to thank my two mothers, Teresa and Leonice, for their
unconditional love and all sacrifices they made to raise my sister Karina and I. There are no words
that I could use to describe my immense gratitude to you, other than, I love you.
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Keywords
Autogenous, grinding, mill, multi-component, ore, blending, mixture, pilot, industrial, AG, SAG,
modelling, simulation
Australian and New Zealand Standard Research Classifications (ANZSRC)
091404 Mineral Processing/Beneficiation 100%
Fields of Research (FoR) Classification
0914 Resources Engineering and Extractive Metallurgy 100%
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Description:Autogenous (AG) and semi-autogenous (SAG) grinding mills have become popular in the mining industry for their ability to provide a high reduction ratio and deal with high tonnage projects in a compact plant layout. AG mills exclusively use ore as grinding media, while in SAG mills steel balls are a
